Optical disc medium having a plurality of sector groups, a recording method thereof and recorder

ABSTRACT

An optical disc medium, including a plurality of sector groups each being made up of multiple contiguous sectors on a track, is provided. In this optical disc medium, the location information of each of those sector groups is divided into a predetermined number of information pieces and distributed to associated sectors on the same track.

TECHNICAL FIELD

The present invention relates to a rewritable optical disc medium andalso relates to a recording method and recorder thereof.

BACKGROUND ART

In recent years, the optical disc has been used more and moreextensively to store video information thereon. Thus, to record a videoof even better quality thereon for a longer time, further increase inrecording density and read/write speeds thereof is strongly demanded. Toachieve this purpose, it is naturally effective to develop a novelstorage medium on which information can be stored at an even higherdensity. However, it is equally important and pressing as well to reducea so-called “overhead area” (e.g., address area), not contributing toincrease in the capacity of information to be stored, as much aspossible.

FIG. 13 illustrates a format for an information track on a conventionaloptical disc. In FIG. 13, the reference numeral 1501 denotes a sector asan information unit, the reference numeral 1502 denotes a non-rewritableheader field recorded in the shape of pits while the optical disc ismanufactured, and the reference numeral 1503 denotes a recording fieldon which information can be written.

In the conventional optical disc, each track has a format in which anumber of sectors 1501 are arranged in line as minimum read/write units.Each of these sectors 1501 consists of a header field 1502 having alength of 128 bytes and a recording field 1503 having a length of 2,569bytes.

Although not shown in FIG. 13, the recording field includes a VFO(variable frequency oscillator) field, a data field on which user datais written, and a buffer field as a redundancy area. The VFO field isprovided to accomplish a phase lock on a PLL (phase-locked loop), whichis needed for reading out a signal recorded.

In the conventional optical disc, to specify what sector on what part ofthe disc a light beam spot is now following, each header field 1502includes location information (i.e., address information representing aspecific location on the optical disc). The location information storedon the header field 1502 indicates the location information of thesector 1501 including the header field. More specifically, as shown inFIG. 13, location information “123456” has been recorded on the headerfield of the sector 1501 specified by an address “123456”. This locationinformation has a length of 4 bytes. An error detection code of 2 bytesis added to the 4-byte location information to see if the locationinformation has been read out correctly.

A signal representing the location information is recorded at the samedensity as the data to be written on the recording field. Accordingly,the signal, as well as the data, needs to be read out using a PLL. Forthis purpose, a VFO field is also provided for the header. When anoptical disc is used as a peripheral storage device for a computer, theinformation stored on the optical disc should be much more reliable ascompared to a situation where the same optical disc is used to record orreplay video or music on/from it. Thus, to consolidate the reliability,the same location information is recorded four times on a single header.As a result, the location information per header has a total length of128 bytes.

As described above, in the conventional optical disc, each sector has tostore the same location information thereon physically four times andalso needs a so-called “overhead area” such as a VFO field. Accordingly,the storage capacity of the optical disc decreases correspondingly.

In order to overcome the problems described above, the present inventionwas made and its object is to provide an optical disc that includes asmallest possible overhead area and can be used effectively to storevideo or any other type of information thereon, and an optical discdrive for such a disc.

DISCLOSURE OF INVENTION

An optical disc medium according to the present invention includes aplurality of sector groups, each being made up of multiple sectors thatare contiguous with each other in a circumferential direction on atrack. In at least some of the sector groups, the location informationthereof is divided into multiple pieces of information and distributedto associated ones of the sectors on the same track.

The location information is preferably represented by a plurality ofidentification marks that are formed as embossed pits. Also, each saidembossed pit is preferably formed between recording fields of associatedones of the sectors that are adjacent to each other in thecircumferential direction on the track.

In a preferred embodiment, each said sector group is made up of 32contiguous sectors.

In another preferred embodiment, each said identification mark assumesone of three mutually different states and represents synchronizationinformation or one-bit information of 1 or 0 by any of the threedifferent states.

In another preferred embodiment, each said identification mark isprovided within a header gap that has a length of 200T or less in adirection in which the track extends, where T is a distance that a lightbeam goes in one reference clock period.

In another preferred embodiment, each said identification mark is madeup of at most two of the embossed pits. The identification marks may bearranged on a centerline of the track on which information is recorded.Alternatively, the identification marks may also be arranged so as to beshifted by a half track pitch from the centerline of the track.

In another preferred embodiment, the optical disc medium has a recordingplane that is divided into a plurality of band-like zones arrangedconcentrically around the center of the disc medium. Multiple tracks areincluded in each said zone. The number of sectors included in each saidtrack changes on a zone-by-zone basis. The number of sectors included ineach said zone is a multiple of the number of sectors that makes up eachsaid sector group.

In another preferred embodiment, the location information of anarbitrary one of the sector groups is distributed to multiple sectorsincluded in the sector group.

In another preferred embodiment, the optical disc medium includes anon-usable dummy sector, and the identification mark included in thedummy sector is provided with invalidity information that makes thesector identifiable as the dummy sector. The invalidity information ispreferably identical with the synchronization information.

In another preferred embodiment, the number of sectors that makes upeach said sector group is a multiple of the number of sectors that makesup a sector block on which logical processing is performed. The sectorlocated at the top of each said sector group is preferably identicalwith the sector located at the top of one of the sector blocks on whichthe logical processing is performed. The logical processing may beeither error correction processing or interleaving processing.Replacement processing is preferably performed on a sector group basis.

In another preferred embodiment, each said sector has its locationinformation recorded thereon.

In another preferred embodiment, the optical disc medium has a recordingplane that is divided into a plurality of band-like zones arrangedconcentrically around the center of the disc medium. Multiple tracks areincluded in each said zone. The number of sectors included in each saidtrack changes on a zone-by-zone basis. In at least one of the zones, thenumber of sectors that makes up the zone is not a multiple of the numberof sectors that makes up each said sector group. In that case, thesectors that make up the zone may include a remainder sector that doesnot belong to any of the sector groups, and the identification mark ofthe remainder sector may be provided with information that makes thesector identifiable as the remainder sector. No information ispreferably recorded on the recording field of the remainder sector.

An optical disc recording method according to the present invention is amethod for performing recording on the optical disc medium according toany of the preferred embodiments described above. In this method, thereplacement processing is performed on a sector group basis.

Another optical disc recording method according to the present inventionis a method for recording information on the optical disc mediumaccording to any of the preferred embodiments described above. In thismethod, each said sector has its own location information recordedthereon.

Still another optical disc recording method according to the presentinvention is a method for recording information on the optical discmedium including the remainder sector. In this method, the informationis not recorded on the recording field of the remainder sector.

Yet another optical disc recording method according to the presentinvention is a method for recording information on the optical discmedium including the remainder sector. In this method, an invaliditysignal is recorded on the remainder sector.

An optical disc recorder according to the present invention is arecorder for performing recording on the optical disc medium accordingto any of the preferred embodiments described above. In this recorder,each said sector has its own location information recorded thereon.

Another optical disc recorder according to the present invention is arecorder for recording information on the optical disc medium includingthe remainder sector. In this recorder, the information is not recordedon the recording field of the remainder sector. An invalidity signalthat makes the sector identifiable as the remainder sector is preferablyrecorded on the recording field of the remainder sector. Alternatively,the invalidity signal may also be recorded on the remainder sector.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a format for an optical disc according to the presentinvention.

FIG. 2 shows a relationship between sectors and a sector group in theoptical disc of the present invention.

FIGS. 3( a) through 3(c) illustrate physical shapes of header fields onthe optical disc of the present invention.

FIGS. 4( a) through 4(d) illustrate exemplary arrangements ofidentification marks that may be used for the optical disc of thepresent invention.

FIG. 5 shows an exemplary arrangement of location information on theoptical disc of the present invention.

FIGS. 6( a) and 6(b) show a buffer track on the optical disc of thepresent invention.

FIGS. 7( a) and 7(b) show a relationship between sector groups andlogical processing blocks on the optical disc of the present invention.

FIG. 8 shows how replacement processing may be performed on the opticaldisc of the present invention.

FIG. 9 shows the details of a sector on the optical disc of the presentinvention.

FIG. 10 shows the end of Zone No. 0 on the optical disc of the presentinvention.

FIG. 11 shows another exemplary arrangement of location information onthe optical disc of the present invention.

FIG. 12 is a block diagram illustrating an embodiment of an optical discdrive according to the present invention.

FIG. 13 shows a sector arrangement on a conventional optical disc.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings.

FIG. 1( a) illustrates a first embodiment of an optical disc accordingto the present invention. As shown in FIG. 1( a), an optical discsubstrate 101 according to this embodiment is a disklike plate, on therecording plane of which multiple information tracks (which will beherein referred to as “tracks”) have been formed. Each of these tracksis made up of a plurality of sectors 104, each including a header field102 and a recording field 103. The header field 102 is made up ofembossed pits (pre-pits) that were formed while the disc was beingmanufactured. The arrangement of these pits represents non-rewritableinformation. On the other hand, the recording field 103 is an area onwhich information can be written and rewritten. As shown in FIG. 1( b),the optical disc substrate 101 of this embodiment includes a pluralityof sector groups 105, each being made up of a predetermined number of(e.g., 32 in this embodiment) sectors.

A state in which a number of tracks are arranged concentrically isillustrated in FIG. 1( a) for the sake of simplicity. Actually, though,the tracks are arranged spirally in this embodiment.

The optical disc substrate 101 includes a phase change type recordingfilm that changes from an amorphous state into a crystalline state, orvice versa, when exposed to laser radiation. Thus, information can bewritten on, or erased from, the recording film. The information is readbased on a difference in the intensity of the light that has beenreflected from respective parts of the optical disc (i.e., based on adifference in reflectance of respective parts of the recording film).

In this embodiment, the revolution of the optical disc substrate 101 iscontrolled by a ZCLV (zoned constant linear velocity) technique.Accordingly, the information recording plane of the optical discsubstrate 101 is divided into a plurality of zones in the radialdirection thereof. These zones are defined so as to have a substantiallyequal size (i.e., width) as measured in the radial direction. Each ofthese zones includes the same number of tracks. However, the number ofsectors included in one zone (or in a track of the zone) is differentfrom the number of sectors included in another zone (or in a track ofthe zone). That is to say, the number of sectors included in anouter-periphery zone or a track thereof is greater than the number ofsectors included in an inner-periphery zone or a track thereof. Morespecifically, the number of sectors included in each track in one zoneis set greater by one than the number of sectors included in each trackin another zone that is adjacent to the former zone and closer to theinner periphery.

The number of revolutions of the optical disc substrate 101 iscontrolled at a constant value within the same zone. However, the numberof revolutions differs from one zone to another. Specifically, thenumber of revolutions of the optical disc substrate 101 in anouter-periphery zone is smaller than in an inner-periphery zone.Accordingly, the linear velocity at which a laser beam spot moves on thedisc or the recording linear density is kept substantially constant fordifferent zones.

Next, the relationship between the sectors 104 and a sector group 105 onthe optical disc medium of the present invention will be described infurther detail with reference to FIG. 2.

In the optical disc of this embodiment, a track is made up of aplurality of contiguous sector groups 105. Each of these sector groups105 consists of 32 sectors 104 that are continuous with each other onthe track. Each of these sectors 104 includes a header field 102 locatedat the top thereof and a recording field 103 that follows the headerfield 102.

In the sector 104 located at the top of each sector group 105, theheader field 102 thereof has been provided with a sync mark “S” that hasbeen formed in the shape of pits (i.e., pre-formatted). When the syncmark “S” is detected by a variation in intensity of the light reflectedfrom the optical disc, the top of the sector group 105 can be located.

In each of the 31 sectors 104 that follow the first sector 104 in thesector group 105, the header field thereof is provided with a positiveor negative mark that has also been formed in the shape of pits. Byallocating information bits “1” and “0” to the positive and negativemarks, respectively, each of the sectors 104 included in each sectorgroup 105 can have one-bit information.

By pre-arranging the sync mark, positive marks and negative marks (i.e.,identification marks) in each sector group 105 in this manner, 31-bitinformation can be recorded on the sector group 105. Furthermore, the31-bit information is divided into 31 pieces, which are distributed tothe 31 sectors 104, respectively.

In this embodiment, the 31-bit information is divided into 19-bit maininformation and 12-bit sub-information, and the 19-bit main informationis used as the location information of the sector group 105. Then, thelocations of 19^(th) power of 2 (=524,288) sector groups 105 can bespecified by the main information thereof. Accordingly, supposing thetop sector group of the overall optical disc has location information ofzero and the following sector groups have location information thatincreases one by one from zero to represent the absolute locations ofthe sector groups 105 by the 19-bit main information, 19^(th) power of 2sector groups 105 can be provided per disc. Thus, if a single sector 104has information of 2,048 bytes and a single sector group 105 hasinformation of 65,536 (=2,048×32) bytes, the maximum amount of data thatcan be accessed through the 19-bit main information is 34 gigabytes.

On the other hand, an error correction code is allocated to the 12-bitsub-information. Even if any bit included in the 19-bit main informationor the 12-bit sub-information is lost because of a defect or some otherreason or even if information is detected erroneously during a readoperation, the error can be corrected by using this error correctioncode. For example, this error correction code may be used for all of theinformation of 31 bits.

If the location information of the sector groups 105 increases one byone monotonically along the tracks, the location information representedby the high-order bits of one sector group 105 is predictable from thelocation information of the previous sector group 105. Accordingly, thelow-order 8 bits of the 12-bit sub-information may also be used as theerror correction code, for example.

Next, exemplary physical shapes of the header fields 102 will bedescribed with reference to FIGS. 3( a) and 3(b).

FIG. 3( a) illustrates an exemplary shape of a sync mark. This sync markconsists of a single pit having a length of 16T, where “1” is areference clock period for recording. A length on the optical disc maybe represented as a multiple of the distance that a light beam goes inone reference clock period (T). Accordingly, a pit having a length of16T means a pit having a size corresponding to 16×T, which is a time ittakes for a light spot formed on the rotating optical disc to move fromone end of the pit to the other on the track.

FIG. 3( b) illustrates an exemplary shape for a positive mark. Thispositive mark is made up of a pit having a length of 8T and another pitthat has been formed so as to be spaced apart from the former pit by 4Tand that has a length of 4T.

FIG. 3( c) illustrates an exemplary shape for a negative mark. Thisnegative mark is made up of a pit having a length of 4T and another pitthat has been formed so as to be spaced apart from the former pit by 4Tand that has a length of 8T.

In reading out location information, when a pit that is sufficientlylonger than any of the pits included in the positive and negative marks(e.g., a pit having a length equal to or greater than that of a pithaving an intermediate length (e.g., 12T) between the length (8T) of thelongest pit in the positive and negative marks and the length of 16T ofthe sync mark pit) has been detected, then the mark detected may bespecified as the sync mark shown in FIG. 3( a).

Also, where two pits having respective lengths of less than 12T havebeen detected consecutively, these two pits should be identified as thelonger pit and the shorter pit. If the longer pit has been detectedbefore the shorter pit, then the mark detected may be specified as thepositive mark shown in FIG. 3( b). Conversely, if the shorter pit hasbeen detected before the longer pit, then the mark detected may bespecified as the negative mark shown in FIG. 3( c).

Alternatively, four detection windows may be provided on a 4T basis andthe signals, detected at the respective centers of these detectionwindows, may be digitized. In that case, the marks detected may bespecified by the digitized signals in the following manner.Specifically, if the digitized signals are “1111”, then the markdetected may be specified as a sync mark. If the digitized signals are“1101”, then the mark detected may be specified as a positive mark. Ifthe digitized signals are “1011”, then the mark detected may bespecified as a negative mark. And if the digitized signals are none ofthese, then the mark detected may be regarded as an error.

According to these detection methods, there is no need to detect theabsolute length every clock period although that detection is usuallyneeded in reading out a data signal. Thus, the PLL does not have to lockonto a signal representing location information. As a result, theredundancy normally caused by a VFO and so on can be saved.

In this manner, the information recorded on each header field 102 ofthis embodiment is represented by a small number of pits as shown inFIGS. 3( a) through 3(c). For this reason, there is no need to lock thePLL for any header field. Accordingly, in reading multiple sectorsconsecutively, if the PLL is once locked in the recording field of apreceding sector and then kept locked even after a succeeding sector hasbeen entered, then the state of the PLL in the preceding sector can alsobe held even in the recording field of the succeeding sector. Thus, thePLL does not have to be locked all over again, and the VFO area may beomitted from the recording field or the length thereof may be minimized.To eliminate the VFO areas from the recording fields in this manner, thespace (i.e., the header gap) between the preceding and succeedingrecording fields should have a length at most equivalent to the responsetime of the PLL. In this embodiment, the response time of the PLL isabout 200T.

Next, exemplary arrangements of the sync marks, positive marks andnegative marks (which will be herein referred to simply as“identification marks” collectively) on the optical disc will bedescribed with reference to FIGS. 4( a) through 4(d).

Suppose the optical disc substrate 101 is an optical disc of aland/groove recording type, which includes both wobbling lands (orgroove portions) and grooves (or inter-groove portions) as its tracksand on which information can be recorded on both the lands and grooves.In that case, as shown in FIG. 4( a), for example, the identificationmarks may be arranged between the lands (or groove portions) and grooves(or inter-groove portions) so as to be on the tracks but shifted fromthe respective centers of the tracks by one half track pitch. In such anarrangement, by reference to a signal level balance between anidentification mark on the disc inner periphery and anotheridentification mark on the disc outer periphery, it is possible todetect how much the light beam following the tracks is shifted from thecenters thereof, and correct the shift, on a sector-by-sector basis.

Alternatively, if no such correction is needed, then thoseidentification marks may also be arranged on the track centerlines ofthe lands and grooves as shown in FIG. 4( b).

Also, to prevent any interference from occurring between adjacentidentification marks, the identification marks may be alternatelyarranged on the lands and on the grooves so as to be shifted from eachother as shown in FIG. 4( c).

On the other hand, the optical disc substrate 101 may be an optical discof the type recording information only on the lands or only on thegrooves. For example, supposing information should be recorded only onthe grooves (or inter-groove portions), the identification marks may bearranged only on the inter-groove portions, or the tracks on which theinformation is recorded, as shown in FIG. 4( d).

According to this embodiment, to access a particular sector in a sectorgroup, first, a given sector group is identified by detecting thelocation information of the sector group. In this manner, the sectorgroup including the target sector can be accessed. Next, the sectors ofthat sector group are counted one by one from the top sector thereof,thereby accessing the target sector.

In the embodiment described above, the identification mark is disposedat the beginning of each sector. However, the identification mark doesnot have to be detected at the beginning of each sector. Alternatively,the identification mark may be disposed at the end of each sector, forexample.

As described above, in the optical disc of this embodiment, each sectorgroup is made up of a predetermined number of (a plurality of) sectors,and the location information of each sector group is divided anddistributed to the respective sectors of the sector group. Theidentification marks, representing the location information of eachsector group, are arranged dispersively and periodically only withinrelatively short areas (having a length of 20T or less) between therecording fields of adjacent sectors. In this manner, the overhead canbe reduced, and the adverse effects of local loss resulting fromdefects, for example, can be minimized, thereby increasing thereliability. More specifically, in the conventional example illustratedin FIG. 13, the area on which user data cannot be written (i.e., theoverhead) accounts for as much as 5% of the overall area of the tracks.In contrast, according to this embodiment, the overhead can be reducedto as low as about 1% of the overall track area.

It should be noted that the location information of each sector groupdoes not have to be distributed to a plurality of sectors that makes upthe same sector group. For example, the location information of eachsector group may also be distributed to a plurality of sectors thatmakes up another sector group, which is located on the same track towhich the former sector group belongs. This point will be described infurther detail later with reference to FIGS. 5 and 11.

Exemplary Zone Arrangement 1

An exemplary zone-by-zone arrangement for an optical disc according tothe present invention is shown in the following Table 1:

TABLE 1 Number of Number of Number of Zone sectors Number of Number ofSector Remainder No. per track Tracks Sectors groups Sectors 0 19 1,88835,872 1,121 0 1 20 1,888 37,760 1,180 0 2 21 1,888 39,648 1,239 0 3 221,888 41,536 1,298 0 4 23 1,888 43,424 1,357 0 5 24 1,888 45,312 1,416 06 25 1,888 47,200 1,475 0 7 26 1,888 49,088 1,534 0 8 27 1,888 50,9761,593 0 9 28 1,888 52,864 1,652 0 10 29 1,888 54,752 1,711 0 11 30 1,88856,640 1,770 0 12 31 1,888 58,528 1,829 0 13 32 1,888 60,416 1,888 0 1433 1,888 62,304 1,947 0 15 34 1,888 64,192 2,006 0 16 35 1,888 66,0802,065 0 17 36 1,888 67,968 2,124 0 18 37 1,888 69,856 2,183 0 19 381,888 71,744 2,242 0 20 39 1,888 73,632 2,301 0 21 40 1,888 75,520 2,3600 22 41 1,888 77,408 2,419 0 23 42 1,888 79,296 2,478 0

In the example shown in Table 1, the number of sectors that makes upeach zone is (the number of sectors per track)×(the number of tracks).The number of sector groups is the quotient given by (the number ofsectors)÷(the number of sectors that makes up each sector group). On theother hand, the number of remainder sectors, which are extra sectorsthat do not make up any sector group, is obtained as the remainder of(the number of sectors)÷(the number of sectors that makes up each sectorgroup). In this case, the remainder sectors that do not make up anysector group have no location information and the absolute locationsthereof are non-specifiable. Thus, the remainder sectors are not used torecord information thereon.

As shown in Table 1, the number of tracks included is the same in eachand every zone on the optical disc of this embodiment. Specifically,1,888 tracks belong to each and every zone. Supposing the number ofsectors per track in a zone is n, the number of sectors that makes upthat zone is 1,888×n, which is a multiple of the number of sectors of“32” that makes up each sector group. That is to say, in thisembodiment, the number of sectors that makes up each zone is a multipleof the number of sectors that makes up each sector group, and the numberof remainder sectors that do not make up any sector group is zero. Thus,each and every sector in a zone can be used without leaving any extrasector.

Exemplary Arrangement 1 of the Location Information of a Sector Group

An exemplary arrangement of the location information in a sector groupon the optical disc of the present invention will be described morespecifically with reference to FIG. 5. In the example shown in FIG. 5, async mark “S” is provided for the top sector among a plurality ofsectors that makes up the sector group 105 specified by an address“123456”. The internal arrangement of any other sector group 105 havinga different address is the same as that of the sector group 105specified by the address “123456”.

As shown in the lower part of FIG. 5, the 31 sectors that follow the topsector include the location information of the sector group 105 to whichthose sectors belong. This location information is represented by theidentification marks of 31 bits b0 through b30. That is to say, the31-bit identification marks have the location information “123456”.

In the same way, in the sector group 105 specified by an address“123457”, the location information “123457” is recorded dispersively onthe 31 sectors 104 that make up the sector group 105.

In this manner, in the example shown in FIG. 5, the address g of eachsector group is specified by the identification marks that aredistributed to a plurality of sectors that makes up the same sectorgroup. On the other hand, in another exemplary location informationarrangement to be described later with reference to FIG. 11, thelocation information of each sector group is distributed to a pluralityof sectors that are included in the previous sector group on the sametrack. The advantages and disadvantages of these two exemplaryarrangements will be mentioned after the arrangement shown in FIG. 11has been described.

Buffer Track

A zone boundary area on the optical disc of the present invention willbe described with reference to FIGS. 6( a) and 6(b).

FIG. 6( a) shows some of the tracks in and between Zones Nos. 0 and 1 .Specifically, the reference numeral 701 denotes the last track belongingto Zone No. 0, the reference numerals 702 and 703 denote buffer tracksand the reference numeral 704 denote the first track belonging to ZoneNo. 1. FIG. 6( b) shows the arrangement of the buffer track 702 shown inFIG. 6( a).

Since Zones Nos. 0 and 1 have mutually different numbers of sectors pertrack, the sector arrangement angles are different from each other inthe zone boundary area. As a result, interference might occur between aheader field in one track and a recording field in another adjacenttrack. To prevent this interference, the buffer tracks 702 and 703 aresometimes provided between the zones as shown in FIG. 6( a). The buffertracks 702 and 703 belong to neither Zone No. 0 nor Zone No. 1 and arenon-usable dummy tracks.

In this embodiment, the header field of each of the sectors that make upthe buffer tracks 702 and 703 as dummy tracks is provided with aninvalidity mark “I”, thereby distinguishing these dummy sectors fromsectors on the tracks having valid information thereon.

Suppose a light beam spot is now moving from Zone No. 0 into Zone No. 1during a write, read or standby mode. In this case, first, the lightbeam spot moves from the last track 701 of Zone No. 0 to enter a dummysector as one of the sectors making up the buffer track 702. Next, whenthe invalidity mark is detected from the header field of the dummysector on the buffer track 702, that sector is regarded as a dummysector. Then, processing of moving into Zone No. 1 is performed so thatthe light beam spot can move into the first track 704 of Zone No. 1quickly.

Furthermore, if the buffer track 702 or 703 is tracked during a seekmode, then the track is recognizable as a dummy track just by detectingthe header field of one sector, not by detecting 32 sectors as needed todetect the location information of a sector group. Accordingly, the nextprocessing can be started very quickly.

The invalidity mark “I” may be formed like the sync mark shown in FIG.3( a), for example. In that case, a given sector is not identifiable asa dummy sector by itself. However, as soon as the same sync mark isdetected from two consecutive sectors, those sectors may be identifiedas dummy sectors. By providing the invalidity mark for the dummy sectorsin this manner, the access performance is improvable.

Logical Processing Block

In recording information on an optical disc, normally some logicalprocessing is performed. For example, an error correction code is addedto correct an error occurring during a read or write operation. Or toprevent errors from being caused locally in a particular part,interleaving processing is performed by rearranging the code sequences.When such an error correction code is added or when such interleaving isperformed, the processing may be carried out using a predeterminednumber of sectors as one block.

The relationship between the sector groups and the logical processingblocks on an optical disc will be described with reference to FIGS. 7(a) and 7(b). FIG. 7( a) shows a relationship between the sector groupsand error correcting blocks, while FIG. 7( b) shows a relationshipbetween the sector groups and interleaving blocks. In FIG. 7( a), thereference numeral 801 denotes the error correcting blocks. In FIG. 7(b), the reference numeral 802 denotes the interleaving blocks.

In writing and/or reading information on/from the optical disc of thepresent invention, the error correction and interleaving may be carriedout on a 16 sector basis. On the other hand, each sector group 105 ismade up of 32 sectors in this embodiment. That is to say, the number ofsectors of “32” that makes up one sector group 105 is a multiple of thenumber of sectors of “16” that makes up one error correcting orinterleaving block 801 or 802. Furthermore, in the optical disc of thisembodiment, the start sector of each sector group 105 is the startsector of the error correcting block 801 or the interleaving block 802.

In actually writing or reading information, the location information isobtained only on a sector group basis. Accordingly, even if just aportion of one sector group 105 needs to be read, that sector groupshould be read entirely and the location information of that sectorgroup should be acquired. For example, if the number of sectors thatmakes up one sector group 105 were not correlated to the errorcorrecting block 801 or interleaving block 802, then the logicalprocessing such as error correction or interleaving should be carriedout on multiple sector groups 105.

According to this embodiment, however, the number of sectors that makesup one sector group is a multiple of the number of sectors that makes upone error correcting or interleaving block. In addition, the startsector of each sector group is identical with the start sector of eacherror correcting or interleaving block. Thus, the performance of theerror correction or interleaving processing is improvable.

Replacement Processing

A method for performing replacement processing on the optical disc ofthe present invention will be described with reference to FIG. 8.

User data is sequentially written on the optical disc while detectingthe location information of the sector groups. Once the user data hasbeen written on a user area, verify processing (i.e., write verify) iscarried out to see if the data has been written successfully. In normalverify processing, if errors have occurred in an error correcting blockat less than a predetermined error rate, then the data written isverified and the next processing is started. However, if there are anydefects on the disc and if errors have occurred in an error correctingblock at the predetermined error rate or more, then the block isregarded as defective and replacement processing is carried out.

In this embodiment, each zone includes a user area and a spare area asshown in FIG. 8. User data is written on the user area, while user data,which should have been written in a part of the user area on/from whichthe data has been once written or read but which has been detected asdefective, is written on the spare area.

For example, the user area may include sector groups 105 specified byaddresses “0” through “999”, while the spare area may include sparesector groups 901 specified by addresses “1000” through “1128”.

Suppose when user data is written on a sector group 105 specified by anaddress “500” and then subjected to verify processing, the latter seconderror correcting block, included in the two error correcting blocksassociated with the sector group, is regarded as a defective block. Inthat case, the former first error correcting block and the second errorcorrecting block are both replaced with one spare sector group 901specified by an address “1000”, and the sector group 105 specified bythe address “500” is also replaced with the same spare sector group 901specified by the address “1000”. This replacement is registered in areplacement list. Optionally, information about the replacement of thefirst and second error correcting blocks associated with the sectorgroup 105 specified by the address “500” may be registered in the list.

In a read operation on the other hand, the sector groups aresequentially read one after another. Specifically, when a sector group105 specified by an address “499” has been read, the next sector groupto be read will be the spare sector group 901 specified by the address“1000” in accordance with the information that has been registered inthe replacement list. When the spare sector group 901 specified by theaddress “1000” has been read, a sector group 105 specified by an address“501” will be read next.

In this manner, according to this embodiment, the replacement processingis carried out on a sector group basis. Thus, while sector groups arebeing read, the alternate sector group can start being read quicklywithout detecting the location information of the original sector groupthat has been replaced with the alternate sector group. As a result, thereplacement processing can be performed at a higher processing speed.

Sector Location Information in Recording Field

Another embodiment of an optical disc according to the present inventionwill be described with reference to FIG. 9. In this embodiment, sectorlocation information 1001, representing the location of a sector, isprovided within the recording field 103, not within the header field102. When information such as user data is written on the recordingfield 103, the sector location information 1001 is recorded at the topof the main information. In this manner, if the sector locationinformation 1001 is recorded at the top of the information to berecorded on the recording field 103, then no VFO area and other areasare needed to read the sector location information 1001. As a result,the degree of redundancy can be reduced.

As the sector location information 1001, information defined by (thelocation information of a sector group)×32+(a sector number in thesector group) may be selected, for example. Alternatively, the sectorlocation information 1001 may also be a logical address different fromthe location information of its sector group, for example. As usedherein, the “logical address” is an address to be read by an apparatus(e.g., host computer) which is located at a higher level than theoptical disc drive.

In this embodiment, when a recorded part is sought, the sector locationinformation 1001 is detected before the location information of itssector group 105 is detected from the 32 sectors of the sector group105. Then, just by reading at least one sector, the absolute location ofthe sector can be specified. Furthermore, when operation processing isperformed after that, the location information of its sector group canalso be confirmed.

In this manner, the location information of each sector is recorded,along with the information to be written, on the optical disc of thisembodiment, thus improving the access performance.

Exemplary Zone Arrangement 2

Another exemplary zone arrangement for an optical disc according to thepresent invention will be described with reference to the followingTable 2:

TABLE 2 Number of Number of Number of Zone sectors Number of Number ofSector Remainder No. per track Tracks Sectors Groups sectors 0 19 1,90036,100 1,128 4 1 20 1,900 38,000 1,187 16 2 21 1,900 39,900 1,246 28 322 1,900 41,800 1,306 8 4 23 1,900 43,700 1,365 20 5 24 1,900 45,6001,425 0 6 25 1,900 47,500 1,484 12 7 26 1,900 49,400 1,543 24 8 27 1,90051,300 1,603 4 9 28 1,900 53,200 1,662 16 10 29 1,900 55,100 1,721 28 1130 1,900 57,000 1,781 8 12 31 1,900 58,900 1,840 20 13 32 1,900 60,8001,900 0 14 33 1,900 62,700 1,959 12 15 34 1,900 64,600 2,018 24 16 351,900 66,500 2,078 4 17 36 1,900 68,400 2,137 16 18 37 1,900 70,3002,196 28 19 38 1,900 72,200 2,256 8 20 39 1,900 74,100 2,315 20 21 401,900 76,000 2,375 0 22 41 1,900 77,900 2,434 12 23 42 1,900 79,8002,493 24

In the optical disc zone arrangement that has already been describedwith reference to Table 1, the number of sectors that makes up each zoneis a multiple of the number of sectors that makes up one sector group.Thus, the zone arrangement has a low degree of flexibility. In contrast,in the zone arrangement shown in Table 2, the number of sectors thatmakes up each zone is not a multiple of the number of sectors that makesup one sector group. In this exemplary zone arrangement, the number oftracks is determined by a track pitch that enables the optical disc toexhibit its highest recording performance, and the number of sectors perzone is determined by the number of tracks. Accordingly, there are somezones that include remainder sectors belonging to no sector groups.

FIG. 10 shows the end of Zone No. 0 on an optical disc having such azone arrangement to a larger scale. Zone No. 0 consists of 1,128 sectorgroups 105 specified by addresses “0” through “1127” and four non-usedremainder sectors 1201.

Each sector 104 in each sector group 105 includes valid information inits header field. On the other hand, each remainder sector 1201 has aninvalidity mark “I” in its header field. Thus, each remainder sector1201 is distinguished from each sector 104 including valid information.

In writing user data, for example, after the data has been written onthe sector group 105 specified by the address “1127”, the light beamspot enters the remainder sectors 1201. As the invalidity marks providedfor the remainder sectors 1201 are detected at this time, the remaindersectors 1201 are skipped. As a result, no data is written on theremainder sectors and the light beam spot moves into Zone No. 1.

Alternatively, to detect the remainder sector 1201 more accurately, aninvalidity signal may be recorded on the remainder sector 1201 withoutskipping the remainder sector 1201. In that case, when the invaliditysignal is detected from the recording field 103, the sector in questionis identifiable as the remainder sector 1201. As the invalidity signalto be written on the recording field of the remainder sector 1201, apattern that does not exist in a modulation code is preferably used. Forexample, if the modulation code adopted is an eight-to-sixteenmodulation code sequence, a continuous pattern of 14T may be recorded asthe invalidity signal.

The invalidity mark “I” may be formed as the sync mark shown in FIG. 3(a). In that case, a given sector is not identifiable as a remaindersector by itself. However, if the same sync mark is detected from twoconsecutive sectors, then those sectors may be regarded as remaindersectors 1201.

As described above, in at least one zone, the number of sectors thatmakes up the zone is not a multiple of the number of sectors that makesup one sector group and the zone is provided with an appropriate numberof remainder sectors when needed. Then, the disc can be designed moreflexibly. Also, by providing an invalidity header for each remaindersector, the access performance is improvable. In addition, by recordingno information on any remainder sector, the processing speed can befurther increased. Optionally, when an invalidity signal is recorded oneach remainder sector, the remainder sector can be detected moreaccurately.

Exemplary Arrangement 2 of the Location Information of a Sector Group

Another exemplary arrangement of the location information of a sectorgroup on the optical disc of the present invention will be describedwith reference to FIG. 11.

An optical disc having the exemplary arrangement shown in FIG. 5 iscompliant with a format in which the location information of a sectorgroup is distributed within the same sector group. In that case,however, to detect the location information of a sector group, aplurality of sectors included in that sector group should be read, thusresulting in a low processing speed.

In the optical disc of this embodiment, the location information of eachsector group is arranged differently from the example shown in FIG. 5.In the other respects, however, the optical disc of this embodiment isthe same as the optical disc described above.

In FIG. 11, a sync mark “S” is provided for the first one of a pluralityof sectors that makes up the sector group 105 specified by an address“123456”, for example. However, the 31 sectors that follow the firstsector do not include the location information of the sector group 105to which those sectors belong but the location information “123457” ofits succeeding sector group 105.

In the same way, as for the sector group 105 specified by an address“123457”, location information “123458” is recorded dispersively on the31 sectors 104 that makes up the sector group 105.

In this manner, a sector group specified by an address “G” includeslocation information “G+1” on the header fields of the sectors thatmakes up the sector group.

In such an arrangement, in reading the location information from thesector group 105 specified by the address “123456”, the locationinformation of the sector group 105 specified by the address “123457”will have been read at the header field 102 of the last sector of thesector group 105 specified by the address “123456”. That is to say,before the sector group 105 specified by the address “123457” isreached, the location information “123457” will have been read.Accordingly, before a sector group is reached, the location informationof that sector group can be detected, thus realizing quick processing.

However, if the location information of each sector group is distributedto a plurality of sectors included in the previous sector group on thesame track, then the sectors, on which the location information of asector group located at the top of each zone should be recorded, cannotbe found at appropriate locations. As a result, such a sector grouplocated at the top of each zone cannot be used to write user data or anyother type of data thereon.

In contrast, in the example shown in FIG. 5, each and every sector groupwithin a zone includes its own location information, and therefore, thesector groups within one zone can be all used.

Optical Disc Drive

FIG. 12 illustrates an embodiment of an optical disc recorder accordingto the present invention. This optical disc recorder is suitablyapplicable for use to write and/or read information on/from the opticaldisc of the present invention described above.

This optical disc recorder includes: an optical head 1401 for focusing alaser beam on a track of an optical disc 101; a circuit A for detectinga sector location, to which the laser beam is irradiated, on the trackby processing the output signal of the optical head 1401; and a circuitB for generating a recording signal based on the information to bewritten on the optical disc 101.

The optical head 1401 includes an element for performing electro-opticalconversion to write information on a recording field of the optical disc101 or to read information from a header field or a recording field ofthe optical disc 101. The optical head 1401 makes a light beam followthe tracks on the optical disc 101, receives the light that has beenreflected from the optical disc 101 and reads and outputs a requiredsignal based on the reflected light.

In accordance with an optical signal that has been output from theoptical head 1401, the circuit A reads the location information of asector from the optical disc 101. More specifically, the circuit Aincludes header detecting means 1402, sector group location informationdetecting means 1403, sector detecting means 1404 and sector locationinformation computing means 1405. In response to the output signal ofthe optical head 1401, the header detecting means 1402 detects andidentifies the header field of the sector irradiated with the lightbeam. The sector group location information detecting means 1403 detectsthe location information of the sector group based on the output of theheader detecting means 1402. In accordance with the output of the headerdetecting means 1402, the sector detecting means 1404 detects and countsthe sectors in the sector group, thereby outputting the number of theparticular sector in the sector group. The sector location informationcomputing means 1405 obtains the location information of the sector inquestion by performing computation on the output of the sector grouplocation information detecting means 1403 and on the output of thesector detecting means 1404.

The circuit B includes signal outputting means 1406, recording signalgenerating means 1407 and recording signal processing means 1408. Thesignal outputting means 1406 outputs user data and a signal such as aninvalidity signal. In accordance with the outputs of the sector locationinformation computing means 1405 and signal outputting means 1406, therecording signal generating means 1407 generates a recording signal. Andthe recording signal processing means 1408 converts the output signal ofthe recording signal generating means 1407 into a recording lasersignal.

Hereinafter, it will be described how to record information on theoptical disc of the present invention by using this optical discrecorder.

First, it will be described how to write data on the optical disc thathas already been described with reference to FIG. 9. Then, the sectorlocation information computing means 1405 obtains and outputs the sectorlocation information based on the sector group location information thathas been output from the sector group location information detectingmeans 1403 and the sector number in the sector group that has beenoutput from the sector detecting means 1404. In this case, the sectorlocation information is defined by (sector group locationinformation)×32+(the sector number in the sector group).

Next, the recording signal generating means 1407 adds thesector-by-sector data, which has been supplied from the signaloutputting means 1406, to the sector location information and thensubjects it to various types of processing, including modulation (e.g.,eight-to-sixteen modulation) and the addition of SYNC (synchronizationcode), thereby generating and outputting a recording signal. Inaccordance with the output signal of the recording signal generatingmeans 1407, information is recorded on the optical disc 101 by way ofthe recording signal processing means 1408.

Next, it will be described how to write data on the optical discincluding the remainder sectors 1201 shown in FIG. 10. The optical discused may be of a type recording no signals on any of the remaindersectors 1201. In that case, when the sector group location informationdetecting means 1403 detects an invalidity mark, the recording signalprocessing means 1408 operates in such a manner as to output norecording laser signals. On the other hand, the optical disc used mayalso be of the type recording an invalidity signal on each of theremainder sectors 1201. In such a situation, when the sector grouplocation information detecting means 1403 detects an invalidity mark,the signal outputting means 1406 outputs an invalidity signal as thesector data. As a result, the invalidity signal is recorded on theoptical disc.

In this manner, the optical disc recorder of this embodiment canappropriately record information on any of the various types of opticaldiscs according to the present invention.

INDUSTRIAL APPLICABILITY

In the optical disc of the present invention, a sector group is made upof a predetermined number of sectors, the location information of thesector group is divided into multiple pieces each including apredetermined amount of information, and the location information isdistributed to the multiple sectors in the sector group. Thus, theoverhead can be reduced and the unwanted effects of local loss due todefects, for example, can also be reduced. As a result, the locationinformation can be detected much more reliably.

Also, according to the recording method of the present invention, whenrecording is performed on the optical disc, replacement processing iscarried out on the basis of a sector group, which constitutes a minimumunit representing the location information. Thus, the replacementprocessing can be performed at a higher processing speed.

In an embodiment where the location information of each sector of theoptical disc is recorded on that sector along with the information to bewritten thereon, that sector can be read without detecting the locationinformation of its sector group. Then, the absolute location of thesector can be specified quickly and the access performance isimprovable. Furthermore, in an embodiment where recording is performedon the optical disc including remainder sectors, no information may berecorded on any of the remainder sectors and the next processing may bestarted immediately. Then, the processing speed can be increased.

Also, in another embodiment where recording is performed on the opticaldisc including the remainder sectors, an invalidity signal may berecorded on each of those remainder sectors. In that case, when theinvalidity signal is detected during a read operation, the given sectoris identifiable as a remainder sector. Since the remainder sector canalso be detected by an identification mark, the remainder sector isdetectible even more accurately.

In an optical disc recorder according to the present invention, wherethe location information of each sector is recorded on that sector alongwith the information to be written thereon, that sector can be readwithout detecting the location information of its sector group. Then,the absolute location of the sector can be specified and the accessperformance is improvable. In an embodiment where recording is performedon the optical disc including remainder sectors, no information may berecorded on any of the remainder sectors and the next processing may bestarted immediately. Then, the processing speed can be increased.Alternatively, an invalidity signal may be recorded on each of thoseremainder sectors. In that case, when the invalidity signal is detectedduring a read operation, the given sector is identifiable as a remaindersector. Since the remainder sector can also be detected by anidentification mark, the remainder sector is detectible even moreaccurately.

1. An optical disc medium comprising a plurality of sector groups, eachsaid sector group being made up of multiple sectors that are contiguouswith each other in a circumferential direction on a track, wherein in atleast some of the sector groups, location information, representing thelocation thereof on the optical disc medium, is divided into multiplepieces of information and distributed to associated ones of the sectorson the same track, wherein said associated ones of the sectorsconstitutes a minimum read/write unit that has its address defined bythe location information, and the location information is preformattedon the optical disc, and wherein the number of sectors that makes upeach said sector group is a multiple of the number of sectors that makesup a sector block on which logical processing is performed.
 2. Theoptical disc medium of claim 1, wherein the location information isrepresented by a plurality of identification marks that are formed asembossed pits.
 3. The optical disc medium of claim 2, wherein each saidembossed pit is formed between recording fields of associated ones ofthe sectors that are adjacent to each other in the circumferentialdirection on the track.
 4. The optical disc medium of claim 2, whereineach said identification mark assumes one of three mutually differentstates and represents synchronization information or one-bit informationof 1 or 0 by any of the three different states.
 5. The optical discmedium of claim 4, wherein the optical disc medium comprises anon-usable dummy sector, and wherein the identification mark included inthe dummy sector is provided with invalidity information that makes thesector identifiable as the dummy sector.
 6. The optical disc medium ofclaim 5, wherein the invalidity information is identical with thesynchronization information.
 7. The optical disc medium of claim 2,wherein each said identification mark is provided within a header gapthat has a length of 200T or less in a direction in which the trackextends, where T is a distance that a light beam goes in one referenceclock period.
 8. The optical disc medium of claim 2, wherein each saididentification mark is made up of at most two of the embossed pits. 9.The optical disc medium of claim 2, wherein the identification marks arearranged on a centerline of the track on which information is recorded.10. The optical disc medium of claim 2, wherein the identification marksare arranged so as to be shifted by a half track pitch from a centerlineof the track on which information is recorded.
 11. The optical discmedium of claim 1, wherein the sectors included in each said sectorgroup are 32 contiguous sectors.
 12. The optical disc medium of claim 1,wherein the optical disc medium has a recording plane that is dividedinto a plurality of band-like zones, the zones being arrangedconcentrically around the center of the disc medium, and whereinmultiple tracks are included in each said zone, the number of sectorsincluded in each said track changing on a zone-by-zone basis, andwherein the number of sectors included in each said zone is a multipleof the number of sectors that makes up each said sector group.
 13. Theoptical disc medium of claim 1, wherein the location information of anarbitrary one of the sector groups is distributed to multiple sectorsincluded in the sector group.
 14. The optical disc medium of claim 1,wherein the sector located at the top of each said sector group isidentical with the sector located at the top of one of the sector blockson which the logical processing is performed.
 15. The optical discmedium of claim 1, wherein the logical processing is error correctionprocessing.
 16. The optical disc medium of claim 1, wherein the logicalprocessing is interleaving processing.
 17. The optical disc medium ofclaim 1, wherein replacement processing is performed on a sector groupbasis.
 18. The optical disc medium of claim 1, wherein each said sectorhas a header field and a recording field that follows the header field,said recording field including a region on which location information ofthe sector is recorded.
 19. An optical disc recorder for performingrecording on the optical disc medium as recited in claim 1, wherein eachsaid sector has a header field and a recording field that follows theheader field, said recording field including a region on which locationinformation of the sector is recorded.
 20. The optical disc medium ofclaim 1, wherein the optical disc medium has a recording plane that isdivided into a plurality of band-like zones, the zones being arrangedconcentrically around the center of the disc medium, and whereinmultiple tracks are included in each said zone, the number of sectorsincluded in each said track changing on a zone-by-zone basis, andwherein in at least one of the zones, the number of sectors that makesup the zone is not a multiple of the number of sectors that makes upeach said sector group.
 21. The optical disc medium of claim 20, whereinthe sectors that make up the zone include a remainder sector that doesnot belong to any of the sector groups, and wherein the identificationmark of the remainder sector is provided with information that makes thesector identifiable as the remainder sector.
 22. The optical disc mediumof claim 20, wherein no information is recorded on the recording fieldof the remainder sector.
 23. An optical disc recording method forrecording information on the optical disc medium of claim 20, whereinthe information is not recorded on the recording field of the remaindersector.
 24. An optical disc recorder for recording information on theoptical disc medium of claim 20, wherein the information is not recordedon the recording field of the remainder sector.
 25. The optical discmedium of claim 20, wherein an invalidity signal is recorded on therecording field of the remainder sector to make the sector identifiableas the remainder sector.
 26. An optical disc recording method forrecording information on the optical disc medium of claim 20, wherein aninvalidity signal is recorded on the remainder sector.
 27. An opticaldisc recorder for recording information on the optical disc medium ofclaim 20, wherein an invalidity signal is recorded on the remaindersector.
 28. The optical disc medium of claim 1, wherein the locationinformation that is distributed to the multiple sectors that makes upone of the sector groups is the location information of another one ofthe sector groups that is located behind the former sector group.
 29. Anoptical disc recording method for performing recording on an opticaldisc medium comprising a plurality of sector groups, each said sectorgroup being made up of multiple sectors that are contiguous with eachother in a circumferential direction on a track, wherein in at leastsome of the sector groups, location information, representing thelocation thereof on the optical disc medium, is divided into multiplepieces of information and distributed to associated ones of the sectorson the same track, wherein said associated ones of the sectorsconstitutes a minimum read/write unit that has its address defined bythe location information and the location information is preformatted onthe optical discs, wherein replacement processing is performed on asector group basis and wherein the number of sectors that makes up eachsaid sector group is a multiple of the number of sectors that makes up asector block on which logical processing is performed.
 30. An opticaldisc recording method for performing recording on an optical disc mediumcomprising a plurality of sector groups, each said sector group beingmade up of multiple sectors that are contiguous with each other in acircumferential direction on a track, wherein in at least some of thesector groups, location information, representing the location thereofon the optical disc medium, is divided into multiple pieces ofinformation and distributed to associated ones of the sectors on thesame track, wherein said associated ones of the sectors constitutes aminimum read/write unit that has its address defined by the locationinformation and the location information is preformatted on the opticaldisc, wherein each said sector has a header field and a recording field,said recording field including a region on which location information ofthe sector is recorded and wherein the number of sectors that makes upeach said sector group is a multiple of the number of sectors that makesup a sector block on which logical processing is performed.